Purification and Characterization of β-N-Acetylhexosaminidase from the Liver of Red Sea Bream

Abstract

β-N-Acetylhexosaminidase was purified to an electrophoretically homogeneous form from the liver of red sea bream Pagrus major and the properties of the purified enzyme were studied. The molecular weight of the enzyme was estimated to be 150, 000 by gel filtration. The enzyme exhibited its maximum activity at pH 4.0, 4.5 and 5.0 toward the substrates p-nitro-phenyl β-N-acetylglucosaminide, chitobiose and bovine submaxillary glycoprotein, respectively. The Km and Vmax of the enzyme for p-nitropheny β-N-acetylglucosaminide were 0.42 mM and 235μmol/min.mg. The enzyme liberated approximately 100% of the N-acetylglucosamine occurring in bovine submaxillary glycoprotein as a minor carbohydrate component, revealing that the N-acetylglucosamine existed at the nonreducing end of the carbohydrate moieties.